A Yard for the Dog

A gentle lesson
on the concepts of
perimeter and area

You just got a new dog!


It’s time to build a little yard for your dog.

Dad says he'll help you build a
fence around the outside.


Mom says she'll help you put
down grass in the inside.

The fence comes in pieces that are 1 yard long.


The grass comes in squares that are 1 yard on each side.

The fence goes around the yard.


The grass covers the inside of the yard.

If you make the dog’s yard 4 yards by 4 yards:


    
    
    
    

How many pieces of fence will you need?


How many pieces of grass will you need?

Let's count!

    1 2 3 4    
       
16         5
15         6
14         7
13         8
       
    12 11 10 9    

grass
1
grass
2
grass
3
grass
4
grass
5
grass
6
grass
7
grass
8
grass
9
grass
10
grass
11
grass
12
grass
13
grass
14
grass
15
grass
16

You'd need:


16 pieces of fence, and
16 pieces of grass.


They are the same!

Do you think this will always
be the case?

What if you make the dog's yard
2 yards by 3 yards?


   
   

How many pieces of fence will you need?
How many pieces of grass will you need?

   
   

You'd need:


10 pieces of fence, and
6 pieces of grass.


More fence than grass!

What if you make the dog's yard
5 yards by 5 yards?


     
     
     
     
     

How many pieces of fence will you need?
How many pieces of grass will you need?

   
   

You'd need:


20 pieces of fence, and
25 pieces of grass.


More grass than fence!
(Even when the yard is square,
unlike before!)

Sometimes you need more fence
and sometimes you need more
grass.

The key things to remember are:


The fence goes around the yard.

The grass covers the inside of the yard.

The fence goes around the
PERIMETER of the yard.


The grass covers the AREA
of the yard.

PERIMETER measures the distance around the yard.


AREA measures the area inside the yard.

PERIMETER
(goes around)
↘

AREA
(covers inside)

How big do you want to make
your dog's yard? 😊



THE END